Question: which river has the steepest tributary
Paraphrase: The steepest tributary is part of which river?
SPARQL (Wikidata): select ?ent where { ?ent wdt:P31 wd:Q4022 . ?ent wdt:P4184 ?obj . ?ent wdt:P974 wd:Q46992264 } ORDER BY DESC(?obj)LIMIT 5